3Com Router User Manual

							DCC Configuration Examples737
DCC Application Using 
ISDN BRI Interface to 
Dial and Providing 
Leased LineTo implement circular DCC, use a B channel on the ISDN BRI interface to provide a 
leased line, and another B channel to implement remote dialing connection. 
As shown in Figure 235, the B2 channel on the interface Bri0 of RouterA is 
connected to the B1 channel on the interface Bri0 of RouterC to provide a leased 
line, whereas the B1 channel is connected to RouterB to implement dialing 
connection. In the ISDN network, configure the correlation of virtual circuits on the 
switches respectively corresponding to RouterA and RouterC, so as to ensure both 
RouterA and RouterC can set up virtual circuit connections to the ISDN network. 
RouterA adopts Circular DCC to call RouterB and RouterC, so do RouterB and 
RouterC. The addresses of RouterA, RouterB and RouterC are respectively 
100.1.1.1, 100.1.1.2, and 100.1.1.3. 
Figure 235   Network for the DCC application using the ISDN BRI interface to dial and 
providing a leased line
1Configure RouterA:
[Router] dialer-rule 1 ip permit
[Router] interface bri 0
[Router-Bri0] ip address 100.1.1.1 255.255.255.0
[Router-Bri0] dialer isdn-leased 2
[Router-Bri0] dialer-group 1
[Router-Bri0] dialer route ip 100.1.1.2 8810152
2Configure RouterB:
[Router] dialer-rule 2 ip permit
[Router] interface bri 1
[Router-Bri1] ip address 100.1.1.2 255.255.255.0
[Router-Bri1] dialer isdn-leased 1
[Router-Bri1] dialer-group 2
[Router-Bri1] dialer route ip 100.1.1.1 8810148
3Configure RouterC:
[Router] dialer-rule 1 ip permit
[Router] interface bri 0
[Router-Bri0] ip address 100.1.1.3 255.255.255.0
[Router-Bri0] dialer-group 1
[Router-Bri0] dialer route ip 100.1.1.1 8810148
Router-to-Router 
Callback for DCCTwo routers implement PPP callback via the serial interfaces across PSTN, and ISDN 
callback with the ISDN caller identification technique across ISDN. 
As shown in the following figure, in the circular DCC implementation, RouterA 
and RouterB are interconnected via the serial interfaces across PSTN, RouterC and 
RouterD are interconnected via ISDN BRI/PRI interfaces across ISDN. RouterA and 
RouterC are specified to be the callback clients, while RouterB and RouterD are 
8810152
8810148
Router ARouter B
Router C
ISDN Bri0Bri1
Bri0
NT1NT1
NT1 
						

							738CHAPTER 51: CONFIGURING DCC
callback servers. RouterA and RouterC use the same address 100.1.1.1, whereas 
RouterB and RouterD use the same address 100.1.1.2.
Figure 236   Network for the DCC application providing router-to-router callback
Solution 1: 
Use Circular DCC to implement PPP callback. The server determines whether to 
originate a return call to a client according to the user names configured in the 
dialer routes.
1Configure RouterA:
[Router] dialer-rule 1 ip permit
[Router] interface serial 0
[Router-Serial0] ip address 100.1.1.1 255.255.255.0
[Router-Serial0] physical-mode async
[Router-Serial0] modem
[Router-Serial0] dialer enable-circular
[Router-Serial0] dialer-group 1
[Router-Serial0] dialer route ip 100.1.1.2 8810052
[Router-Serial0] link-protocol ppp
[Router-Serial0] ppp pap local-user usera password simple usera
[Router-Serial0] ppp callback client
2Configure RouterB:
[Router] dialer-rule 2 ip permit
[Router] local-user usera password simple usera
[Router] interface serial 1
[Router-Serial1] ip address 100.1.1.2 255.255.255.0
[Router-Serial1] physical-mode async
[Router-Serial1] modem
[Router-Serial1] dialer enable-circular
[Router-Serial1] dialer-group 2
[Router-Serial1] dialer route ip 100.1.1.1 user usera 8810048
[Router-Serial1] dialer callback-center user
[Router-Serial1] link-protocol ppp
[Router-Serial1] ppp authentication-mode pap
[Router-Serial1] ppp callback server
Solution 2: 
Use Circular DCC to implement PPP callback. The server dynamically creates dialer 
routes and originates return calls to the clients according to the dialer numbers.
1Configure RouterA:
[Router] dialer-rule 1 ip permit
[Router] interface serial 0
Router B
Modem
ISDNModem
PSTN
Networking for ISDN caller ID callbackNetworking for PPP callback
88101488810152 88100488810052
Router A
Router C
Router D
Callback ClientCallback Server Serial0 Serial1
Bri0
Bri1 Callback Client
Callback Server NT1
NT1 
						

							DCC Configuration Examples739
[Router-Serial0] ip address 100.1.1.1 255.255.255.0
[Router-Serial0] physical-mode async
[Router-Serial0] modem
[Router-Serial0] dialer enable-circular
[Router-Serial0] dialer-group 1
[Router-Serial0] dialer route ip 100.1.1.2 8810052
[Router-Serial0] link-protocol ppp
[Router-Serial0] ppp pap local-user usera password simple usera
[Router-Serial0] ppp callback client
2Configure RouterB:
[Router] dialer-rule 2 ip permit
[Router] local-user usera password simple usera callback-number 
8810048 
[Router] interface serial 1
[Router-Serial1] ip address 100.1.1.2 255.255.255.0
[Router-Serial1] physical-mode async
[Router-Serial1] modem
[Router-Serial1] dialer enable-circular
[Router-Serial1] dialer-group 2
[Router-Serial1] dialer route ip 100.1.1.1 user usera 8810048
[Router-Serial1] dialer callback-center dial-number
[Router-Serial1] link-protocol ppp
[Router-Serial1] ppp authentication-mode pap
[Router-Serial1] ppp callback server
Solution 3: 
Use Circular DCC to implement ISDN caller identification callback.
1Configure RouterA:
[Router] dialer-rule 1 ip permit
[Router] interface bri 0
[Router-Bri0] ip address 100.1.1.1 255.255.255.0
[Router-Bri0] dialer-group 1
[Router-Bri0] dialer route ip 100.1.1.2 user usera 8810152
2Configure RouterB:
[Router] dialer-rule 2 ip permit
[Router] interface bri 1
[Router-Bri1] ip address 100.1.1.2 255.255.255.0
[Router-Bri1] dialer-group 2
[Router-Bri1] dialer route ip 100.1.1.1 user usera 8810148
[Router-Bri1] dialer call-in 8810148 callback
Router-to-PC Callback 
for DCCA router and a PC implement PPP callback via the serial interfaces over PSTN. As 
shown in the following figure, the PC and RouterA are interconnected via the 
modems across PSTN. Circular DCC is adopted in this case. The PC is specified to 
be the callback client whereas RouterA to be the callback server. They implement 
callback according to the configuration of the dialer route command. RouterA 
uses the address 100.1.1.1 and the PC accepts the address assigned by RouterA. 
						

							740CHAPTER 51: CONFIGURING DCC
Figure 237   Network for the DCC application providing router-to-PC callback
1Configure the PC:
aConfigure the modem connected to the PC to be in “autoanswer mode”. 
bSelect Start > Programs > Accessories > Communications > Dialup network. 
cClick Set up new connection in the Dialup network window. 
dSelect the Server type page in the established new connection, and perform 
the following operations:
■Select the option [PPP]
■Set the [Logon network] option as unchecked
■Set the [Start software compression] as unchecked
eSelect TCP/IP setting in the Server type page, and perform the following 
operations:
■Check the option [Server allocated with IP address]
■Set the [Use IP head pointer compression] option as unchecked
■Set the [Use default gateway of the remote network] option as unchecked
2Configure RouterA:
[Router] dialer-rule 1 ip permit
[Router] local-user userpc password simple userpc
[Router] interface serial 0
[Router-Serial0] ip address 100.1.1.1 255.255.255.0
[Router-Serial0] remote address 100.1.1.2
[Router-Serial0] physical-mode async
[Router-Serial0] modem
[Router-Serial0] dialer enable-circular
[Router-Serial0] dialer-group 1
[Router-Serial0] dialer route ip 100.1.1.2 user userpc 8810052 
[Router-Serial0] dialer callback-center user
[Router-Serial0] link-protocol ppp
[Router-Serial0] ppp authentication-mode pap
[Router-Serial0] ppp pap local-user Router password simple Router
[Router-Serial0] ppp callback server
NT Server-to-Router 
Callback for DC
C
A router and an NT server implement PPP callback via the serial interfaces across 
PSTN.
As shown in Figure 238, RouterA and the NT server are interconnected via the 
modems across PSTN. In this case, circular DCC is adopted. RouterA is specified as 
the callback client and the NT server as the callback server. Callback is 
implemented according to the configuration of the dialer route command. The 
NT server uses the address 100.1.1.254, and RouterA accepts the address assigned 
by the NT server.
PSTN8810052 8810048
PCRouter A
ModemModem
Callback Server
Callback ClientSerial0 
						

							DCC Configuration Examples741
Figure 238   Network for the DCC application providing NT server-to-router callback
1Configure RouterA:
[Router] dialer-rule 1 ip permit
[Router] interface async 0
[Router-Async0] async mode protocol
[Router-Async0] link-protocol ppp
[Router-Async0] ppp callback client
[Router-Async0] ppp pap local-user Router password simple Router
[Router-Async0] ip address ppp-negotiate
[Router-Async0] dialer enable-circular
[Router-Async0] dialer-group 1
[Router-Async0] dialer route ip 100.1.1.254 8810052 
2Configure NT server:
aConfigure the modem connected to the PC to be in “autoanswer mode”, open 
[Start/Programs/Accessories/Communications/Dialup Network], click [Set up 
new connection] in the [Dialup Network] window, select the [Server type] page 
in the established new connection, and perform the following operations:
bFirst, open the [Network attributes/Services] page, add “remote access server” 
in it and configure RAS attribute, click the  button to install the modem, 
and set the modem attribute to “Dial-out and dial-in”. If the modem has been 
installed, click . Click the  button on the right to set the 
network attributes of RAS, including:
■Select “TCP/IP” in both [Dial-out protocol] and [Server setting].
■Click  on the right to configure an address assignment method 
for the dial-in client. It can be either “Use DHCP” or “Use static address 
set”.
■Select [Allow any authentication] to configure “Encryption setting”.
cThen, select the menu bar [Management tools/Server management] to enable 
remote accessing service.
dFinally, select the menu bar [Management tools/Remote access management] 
to enter the management interface, select [Users/Authorities] in it, and choose 
the user that can implement remote access. Three callback attributes are 
available, including:
■No callback
■Set by the dial-in party: The ppp callback ntstring dial-number 
command should be configured on the router if this method is selected.
■Preset to number: If this method is selected, the dial-number set on the 
router will be invalid and the NT system will dial the preset number when 
placing a return call.
PSTN8810052 8810048
Router AModemModem
Callback Server Callback ClientAsync1 
						

							742CHAPTER 51: CONFIGURING DCC
Dial Number Circular 
Standby and Internet 
Access for DCCIn PSTN, the dial number circular standby is fulfilled through configuring the 
dialer route command at the dialing side. The access side provides the 
accessing service for DCC via the asynchronous serial interface, and adopts the 
PAP authentication to authenticate the validity of the dialing party. In ISDN, single 
dialer number and CHAP authentication are adopted, and other configurations are 
similar to the PSTN side.
As shown in the following figure, RouterB and RouterD work as access server, 
RouterA and RouterC at the dialing side accept the negotiated addresses assigned 
by the remote ends. The address pool for allocation is in the range of 100.1.1.1 to 
100.1.1.16. RouterB and RouterD use the address 100.1.1.254, and obtain the 
dialer numbers 8810048 to 8810055 from the telecommunications service 
provider. ISDN dial number is 8810148, which provides services for 16 network 
users.
Figure 239   Network for the DCC application providing dial number circular standby and 
accessing service
Solution 1: 
Configure dial number circular standby on the dialing parties, adopt Circular DCC 
to set up connections on the 8 asynchronous serial interfaces at the access side, 
and configure the DCC parameters on the dialer interfaces. 
1Configure RouterA:
[Router] dialer-rule 1 ip permit
[Router] local-user userb password simple passb
[Router] interface serial 0
[Router-Serial0] physical-mode async
[Router-Serial0] modem
Modem
Modem
Modem
Modem
Modem
8810148
Provide accessing services on ISDN PRI interface Provide accessing service on asynchronous interfaces8810048
8810055 8810054 8810053 8810052 8810051 88100508810049
Modem
Modem
ModemPSTN Router A
ISDN
Modem
Modem
Async0 to
Async7
Serial2:15Router B
Router C
Router D Serial0
Bri0
Router
NT1
NT1
Internet
Internet
PCModem
……
Serial0
Router 
						

							DCC Configuration Examples743
[Router-Serial0] ip address ppp-negotiate
[Router-Serial0] dialer enable-circular
[Router-Serial0] dialer-group 1
[Router-Serial0] dialer route ip 100.1.1.254 8810048
[Router-Serial0] dialer route ip 100.1.1.254 8810049
……
[Router-Serial0] dialer route ip 100.1.1.254 8810055
[Router-Serial0] link-protocol ppp
[Router-Serial0] ppp pap local-user user1 password simple user1
2Configure RouterB:
[Router] dialer-rule 2 ip permit
[Router] aaa-enable
[Router] aaa authentication-scheme local-first
[Router] aaa accounting-scheme optional
[Router] local-user user1 password simple pass1
[Router] local-user user2 password simple pass2
……
[Router] local-user user16 password simple pass16
[Router] ip pool 1 100.1.1.1 100.1.1.16
[Router] interface dialer 0
[Router-Dialer0] ip address 100.1.1.254 255.255.255.0
[Router-Dialer0] remote address pool 1
[Router-Dialer0] dialer enable-circular
[Router-Dialer0] dialer-group 2
[Router-Dialer0] link-protocol ppp
[Router-Dialer0] ppp authentication-mode pap
[Router-Dialer0] ppp pap local-user userc password simple passc
[Router-Dialer0] interface async 1
[Router-Async1] dialer circular-group 0
[Router-Async1] link-protocol ppp
[Router-Async1] ppp authentication-mode pap
[Router-Async1] interface async 2
[Router-Async2] dialer circular-group 0
……
[Router-Async7] interface async 8
[Router-Async8] dialer circular-group 0
[Router-Async8] link-protocol ppp
[Router-Async8] ppp authentication-mode pap
3Configure subscriber PC:
aInstall a modem in a subscriber PC, configure it to be in “autoanswer mode”, 
open [Start/Programs/Accessories/Communications/Dialup network], click [Set 
up new connection] in the [Dialup network] window, and select [Server type] in 
the established new connection, and perform the following operations:
■Select the option [PPP]
■Set the option [Login network] as unchecked
■Set the option [Start software compression] as unchecked
bSelect [TCP/IP setting] in the [Server type] page, and perform the following 
operations:
■Check the option [Server allocated with IP address]
■Set the [Use IP head pointer compression] option as unchecked
■Set the [Use default gateway of the remote network] option as unchecked 
						

							744CHAPTER 51: CONFIGURING DCC
cStart dialing, and input the user name user1 and the password pass1.
Solution 2: 
The dialing side uses a single number to dial, and the accessing side uses circular 
DCC to set up the connection via the ISDN PRI interface. Configure the DCC 
parameters on the dialer interface.
1Configure RouterC:
[Router] dialer-rule 1 ip permit
[Router] local-user userb password simple passb
[Router] interface bri 0
[Router-Bri0] ip address ppp-negotiate
[Router-Bri0] dialer-group 1[Quidway-Bri0] dialer enable-circular
[Router-Bri0] dialer route ip 100.1.1.254 8810148
[Router-Bri0] link-protocol ppp
[Router-Bri0] ppp chap user user1
[Router-Bri0] ppp chap password simple pass1
2Configure RouterD:
[Router] dialer-rule 2 ip permit
[Router] local-user user1 password simple pass1
[Router] local-user user2 password simple pass2
……
[Router] local-user user16 password simple pass6
[Router] ip pool 1 100.1.1.1 100.1.1.16
[Router] controller e1 2
[Router-E1-2] pri-set
[Router-E1-2] interface serial 2:15
[Router-Serial2:15] ip address 100.1.1.254 255.255.255.0
[Router-Serial2:15] remote address pool 1
[Router-Serial2:15] dialer enable-circular
[Router-Serial2:15] dialer-group 2
[Router-Serial2:15] link-protocol ppp
[Router-Serial2:15] ppp authentication-mode chap
[Router-Serial2:15] ppp chap user userb
[Router-Serial2:15] ppp chap password simple passb
Logical Interface 
Standby through Dialer 
route for DCCRouterA and RouterB are directly connected via the serial interfaces. At the same 
time, RouterA forms a dialup connection with RouterB via a modem through 
PSTN. RouterB cannot call RouterA via dialing.
As shown in Figure 240, a logical interface is generated through configuring the 
dialer route command on RouterA. This interface can be used as either the 
standby interface for other interfaces or the main interface. The port Serial0 on 
RouterA is used as the dialer interface, and Serial1 is connected to RouterB 
through straightforward DDN. The address of Serial0 on RouterA is 100.1.1.1, and 
the address of the Serial1 connected to DDN is 200.1.1.1. The address of the 
dialer interface on RouterB is 100.1.1.2, and the address of the interface 
connected to DDN is 200.1.1.2. 
						

							DCC Configuration Examples745
Figure 240   Network for the DCC application providing logic interface standby through 
dialer route
Solution 1: 
Adopt circular DCC and use the logic interface configured through the dialer 
route command as the standby interface.
1Configure RouterA:
[Router] dialer-rule 1 ip permit
[Router] interface serial 0
[Router-Serial0] physical-mode async
[Router-Serial0] modem
[Router-Serial0] ip address 100.1.1.1 255.255.255.0
[Router-Serial0] dialer enable-circular
[Router-Serial0] dialer-group 1
[Router-Serial0] dialer route ip 100.1.1.2 8810060 logic-channel 1
[Router-Serial0] interface serial 1
[Router-Serial1] ip address 200.1.1.1 255.255.255.0
[Router-Serial1] link-protocol ppp
[Router-Serial1] standby logic-channel 1
2Configure RouterB:
[Router] dialer-rule 2 ip permit
[Router] interface serial 0
[Router-Serial0] physical-mode async
[Router-Serial0] modem
[Router-Serial0] ip address 100.1.1.2 255.255.255.0
[Router-Serial0] dialer enable-circular
[Router-Serial0] dialer-group 2
[Router-Serial0] dialer route ip 100.1.1.1 8810059 logic-channel 1
[Router-Serial0] interface serial 1
[Router-Serial1] ip address 200.1.1.2 255.255.255.0
[Router-Serial1] link-protocol ppp
[Router-Serial1] standby logic-channel 1
Solution 2: 
Adopt circular DCC and use the logical interface configured through the dialer 
route command as the main interface.
1Configure RouterA:
[Router] dialer-rule 1 ip permit
[Router] interface serial 0
[Router-Serial0] physical-mode async
[Router-Serial0] modem
[Router-Serial0] ip address 100.1.1.1 255.255.255.0
[Router-Serial0] dialer enable-circular
[Router-Serial0] dialer-group 1
PSTN8810060
Router A
Router B
ModemModem
Serial1 Serial0
Serial0
Serial1 8810059 
						

							746CHAPTER 51: CONFIGURING DCC
[Router-Serial0] dialer route ip 100.1.1.2 8810060 logic-channel 1
[Router-Serial0] logic-channel 1
[Router-logic-channel1] standby interface serial 1
[Router-logic-channel1] interface serial 1
[Router-Serial1] ip address 200.1.1.1 255.255.255.0
[Router-Serial1] link-protocol ppp
2Configure RouterB:
[Router] dialer-rule 2 ip permit
[Router] interface serial 0
[Router-Serial0] physical-mode async
[Router-Serial0] modem
[Router-Serial0] ip address 100.1.1.2 255.255.255.0
[Router-Serial0] dialer enable-circular
[Router-Serial0] dialer-group 2
[Router-Serial0] dialer route ip 100.1.1.1 8810059 logic-channel 1
[Router-Serial0] logic-channel 1
[Router-logic-channel1] standby interface serial 1
[Router-logic-channel1] interface serial 1
[Router-Serial1] ip address 200.1.1.2 255.255.255.0
[Router-Serial1] link-protocol ppp
Troubleshooting DCCModem does not dial when the router forwards the data, so the DCC 
dialup connection cannot be set up.
Do the following:
■Check whether the modem and phone cable connections are correct, and 
whether the modem initialization process is correct.
■For the synchronous/asynchronous serial interface, check whether it is 
configured to asynchronous and dialing mode.
■Check whether DCC has been enabled on the dial interface.
■Check whether the corresponding dialer route or dialer number command 
has been configured for the packet.
The remote end cannot be pinged after the modem is connected.
Do the following:
■Check whether the same encapsulation protocol is configured on the local and 
remote ends, and whether the configured PPP authentication parameters are 
correct. Use the 
debugging ppp all command to enable PPP debugging to 
view the PPP negotiation process, and make sure that the PPP negotiation 
parameters are correct.
■Check whether the network address has been correctly configured on the dial 
interface (physical interface or dialer interface).
■Check whether DCC has been enabled on the dial interface.
■Check whether the commands dialer-group and dialer rule have been 
configured, and whether the configurations are correct. Make sure that 
dialer 
rule
 is configured to permit the packet and the two commands are associated.
■Use the commands debugging dialer event and debugging dialer packet 
to debug DCC, and locate the problem according to the output information.